Stabilization of trichloroethylene



Jdrooarbons. I

Patented Aug. 4, 1931 i UNITED STATES PATENTQ OFFICE CHARLESDANGEIMAJER, OF NIAGARA FALLS, NEW YORK, ASSIGNOR, BY MESNE AS-SIGNKENTS, "1'0 THE ROESSLER & HASSLAC HER CHEMICAL COMPANY, OF NEWYORK, Y., A CORPORATION OF DELAWARE STAIBEIZATION 0F TRICHLOBOETHYLENENo Drawing.

This invention relates to a new composition of matter comprising-trichloroethylene esses and also make it more diflicult to storebecause of the corrosive properties of the decomposition products.

I have discovered that trichloroethylene can be rendered stable for.storage and dis-- .tillation and the development of objectiona bledegrees of acidity largely avoided by the addition of-gasolineor relatedpetroleum hy- I am aware thatother stabilizers have been proposed andused, such as xylene, toluene,

etc. I have tried these and found that they are not satisfactoryprimarily because they are not efficient stabilizers and secondarily,

0.25%- by volume was added to trichloroethylene having an acidity of17.0. After seven because they are more expensive and must be used inlarger concentrations than gasoline Emamples As a measure of theinstability of trichloroethylene the acidity of a 25cc. sample in termsof 0.01 normal sodium hydroxide is used. The indicator isphenolphthalein. Thus, for example, if 25 cc. of a sample requires 10cc. of 0.01 normal sodium hydroxide solution foroomplete neutralizationits is givenas 10. e batch of crude freshly manufactured undistilledtrichloroethylene had an original acidity of 0A, which rose to 300 afterstoring for 52 days and to much over 1000 after 14 months storage.

2. A portion of the same batch asunder 1 was distilled and 0.1% byvolume of gasoline was added. The original acldity was Applicationfiledl'anuary 11, 1929. Serial No. 831,345..

very low and after 52 days was 0.8 and after 14 months it was 4.2."

3. A portion of the same batch as under 1 was distilled and then a fewdrops of highacid .trichloroethylene was added, also 0.5% by volume ofgasoline. After two weeks the acidity'was 0.9; after 4 weeks is was 0.7and after seven weeks it was 0.5. At the end of 1411101115115 theacidity was 2.5.

' 4. To a batch of crude .freshly manufactured undistilledtrichloroethylene 0.25% by volume of gasoline was added. A few drops .ofhigh-acid unstabilized trichloroet'hylene was added after disti1ling thestabilized crude material. The acidity after 2, 4, and 7 weeks and 14months was 0.6,04, 0.6 and 1.5'

respectively.

5. Normal heptane to the extent of 0.25%

by volume was added to a. batch of trichloroethylene having an initialacidity of 0.6.

After 7 months the acidity was unchanged. 6. Ordinary kerosene to theextent of 0.25% by volume was added to tri'chloroethylene of-0.6acidity. After seven months there was no change'in the acidity.

7. Ordinary kerosene to the extent of months the acidity was only 1.8.

I have found Nujol and higher boiling lubricating oils to be effectivestabilizers but they-have the disadvantage that they boil at hightemperatures and therefore do not distill over with thetrichloroethylene in effective amounts if that is the method ofrecovery. In eneral gasoline, either straight run or crac ed and havingboiling ranges between about 100F. and 450 F. will be preferable.However, higher boiling hydrocarbon fractions, such as kerosene, aresuitable for many purposes and also lower fractions having lower boilinglimits than 100 F.

High-acid trichloroethylene is trichloroethylene that has suffered muchdecomposition and has a very'high content of acidic substances. It hasbeen found that the decomposition products auto-catalyze or pro mote thedecomposition of trichloroethylene when present in very smallquantities. The object of adding a few dropsof'high acid I wetrichloroethylene in examples 3 and 4 was to test the stabilizing effectof gasoline on trichloroethylene contaminated with decompositionpromoters. The results show that gasoline is a good stabilizer underthese conditions.

Gasoline may be added to the trichloroethylene before distillation orafter distillation. indeed, gasoline can be added'whenever thetrichloroethylene shows indications of increasing acidity. Thus, wherethis solvent is used for extraction or other purposes it may beadvisable to add small amounts of asoline from time to time to keep thetrich oroethylene sweet by inhibiting further acid formation andreducing that already present.

This invention is not limited to any specific proportions ofhydrocarbons and trichloroethylene. As little as 0.01% by volume ofgasoline or similar liquid hydrocarbons will efi'ect marked stability.For most practical purposes, however, it is necessary to have at least0.025%and preferably over 0.05% by volume of stabilizer in thetrichloroethylene. For certain purposes it is desirable to add as muchas or more of stabilizer in which case a mixtureresults having anexceedingly high acid stability and at the same time the flammability ofthe hydrocarbon fraction is greatly reduced.

The stabilizer may be any hydrocarbon material, single compound ormixture, that is liquid at room temperature and belonging to thealiphatic series. Either straight run or cracked gasoline may be used.In the claims the term gasoline is intended to cover any aliphatichydrocarbon material within the boiling range of 100 and 450 F.

Claims:

1. Composition of matter comprising trichloroethylene and stabilizingamounts of gasoline.

2. Composition of matter comprising upwards of 90% trichloroethylene andthe remainder aliphatic petroleum hydrocarbon material. r

3. Composition of matter gomprising upwards of 90% trichloroethylene andthe remainder a petroleum hydrocarbon material having a boiling rangebetween about 100 F. and 450 F.

4. Composition of matter comprising up- Wards'of 90% trichloroethyleneand the remainder gasoline.

5. Process of stabilizing trichloroethylene which comprises addinggasoline thereto.

6. Process of stabilizing trichloroethylene which comprises distillingtrichloroethylene in contact with gasoline. 7. Process for reducing theacidity of trichloroethylene which comprises treating trichloroethylenewith gasoline.

8. Process for reducing the acidity of trichloroethylene which comprisesdistilling trichloroethylene in contact with' gasoline.

9. Composition of matter consisting of trichloroethylene and betweenabout 0.01% and 50% by volume of gasoline.

Signed at Niagara Falls in the county of Niagara and State of New Yorkthis 7th day of January A. D. 1929.

CHARLES DANGELMAJ ER.

